Light-emitting devices such as vertical-cavity surface-emitting lasers (VCSELs) are known in the art. The active region of a VCSEL has a quantum well structure composed of one or more quantum well layers interleaved with a corresponding number of barrier layers. Each quantum well layer forms a quantum well with the adjacent barrier layers. The quantum well captures and confines carriers (electrons and holes), which subsequently radiatively recombine to generate light.
The active region of a conventional VCSEL that generates light at a wavelength of 850 nanometers (nm) has a quantum well structure composed of quantum well layers of gallium arsenide (GaAs) and barrier layers of aluminum gallium arsenide (AlGaAs). However, using indium gallium arsenide (InGaAs) instead of GaAs as the material of the quantum well layers is advantageous because strain increases the differential gain and reduces the transparency current, both of which are beneficial to high speed operation, reliability and driver circuitry. The quantum well structure of a typical conventional VCSEL that generates light at a wavelength of 980 nm has quantum well layers of indium gallium arsenide (InGaAs) and barrier layers of gallium arsenide (GaAs) or quantum well layers of indium gallium arsenide (InGaAs) and barrier layers of gallium arsenide phosphide (GaAsP).
However, a conventional 980 nm VCSEL has a lower maximum modulation speed and inferior temperature performance compared to a conventional 850 nm VCSEL.
Accordingly, what is needed is a way to increase the maximum modulation speed and to improve the temperature performance of 980 nm VCSELs and other light-emitting devices that generate light at this wavelength.